1. Field of the Invention
The present invention relates generally to a method for welding first and second metallic materials one of which having a surface with an optical pattern disposed thereon and, more particularly, to a method for welding first and second electroformed materials each having the optical pattern on at least one surface thereof while minimizing distortion and damage to the optical patterns as a result of the weld.
2. Prior Art
It is well known that many nickel-based alloys can be joined by a host of welding techniques including arc, solid state, electron-beam and laser beam. When it is required to maintain certain properties after the welding process, the proper choice of welding processes are limited. The following properties and geometric considerations are important when addressing the functionality of certain optical and structural components. In addition to minimizing overall component thermal distortions, an important structural consideration is the retention of the materials original metallurgical and mechanical properties such as those which correlate with fine grain structure, formability and low cycle fatigue. Fine grains will grow when subjected to extended levels of high temperature as might be experienced in a furnace, improperly cooled machining procedures, and high heat input welding processes.
To assure a trouble free final assembly process of complex hardware, it is good design practice to maintain geometric dimensions and tolerances of multiple components and subassemblies. This may be a potential problem when components and/or subassemblies require one or more welding procedures. Welding procedures can readily cause distortions in the components and/or subassemblies, such as warping of the components. Such distortions can result in dimensions and tolerances that do not meet specifications. This problem can be amplified if the component parts have residual stresses present resulting from a forming process or from unfavorable concentration of alloy constituents.
In addition to structural and geometric considerations, the surfaces of these component parts may be optically finished and may ultimately be coated. The welding process and any warping associated therewith cannot be tolerated because it disturbs the optical finish of the welded components and thus compromises the integrity of the optical finish or effects the material in ways which may preclude any subsequent coating process. The optical finish of the surfaces is the critical quality attribute when considering end use functionality.